Stacking device for printing machines



May 27, 1958 K. BLATTNER EIAL STACKING DEVICE FOR PRINTING MACHINES Filed May 10, 1954 7 Sheets-Sheet 1 Inventq/y A/fikl BLiTr/V A/FRNER IDAUL KocH Auk- 12K01 May 27, 1958 K. BLATTNER ETAL 2,336,413

STACKING DEVICE FOR PRINTING MACHINES Filed May 10. 1954 7 Sheets-Sheet 2 Inventors KARL Bzk'rrNA-R /\//?/VR PAUL KocH Hr romvtr y 1958 K. BLATTNER El'AL 2,836,418

' STAUKING DEVICE FOR PRINTING MACHINES Filed May 10, 1954 '7 Sheets-Sheet 3 fizz/227ml": A HRL 5A arr/v5? A/ERNER R4411. KOCH May 1958 K. BLATTNER ETAL 2,836,418

smcxmc DEVICE FOR PRINTING MACHINES Filed May 10, 1954 7 Sheets-Sheet 4 7 I Inventor? 59x4 BAA'TrAAs-R 77a 77 A/fmvsk 840g. Kocu 3/ MM 1. Ha

May 1953 K. LATTNER ETAL 2,836,418

S TACKING DEVICE FOR PRINTING MACHINES Filed May 10, 1954 7 Sheets-Sheet 5 May 1958 K. BLATTNER ETAL 2,836,418

STACKING DEVICE FOR PRINTING MACHINES 7 Sheets-Sheet 6 Filed May 10. 1954 s H n W M f p KHH MH Q PM r fi May 1958 K. BLATTNER ETAL 2,836,418

STACKING DEVICE FOR PRINTING MACHINES '7 Sheets-Sheet 7 Filed May 10, 1954 3 MM Wm N mi 87A r VrP r m m aw R United States Patent O i STACKING DEVICE FOR PRINTING MACHINES Karl Bliittner and Werner Paul Koch, Offenbach (Main),

Germany, assignors to Faber & Schleicher Aktiengesellschaft, Offenbach (Main), Germany, a firm Application May 10, 1954, Serial No. 428,629 Claims priority, application Germany May 22, 1953 18 Claims. (Cl. 271-68) removed and a new stack table placed in its stead. The

temporary depositing means are then withdrawn so that the sheets which have meanwhile collected thereon fall onto the empty table, so that the delivery and the stacking of the oncoming sheets may continue without interruption.

It is usual, in printing machines, to provide such temporary supporting means in the form of grates, or auxiliary tables or table tops made of thin plates, but for the purpose of this specification and for the sake of greater simplicity these temporary means will hereinafter be generally referred to as grates. It is thus to be understood, that the term grate as used hereinafter also includes other auxiliary means, such as the afore mentioned tables, table tops, comb-like structures and the like which may be used for the same purpose as the device in accordance with the invention.

For the preliminary deposition of the sheets during the interval in which the stacking tables are being exchanged, the grates or comb-like structures which have been used consisted of long thin slats joined at one or both ends by cross strips, and it is common practice in printing machines, to provide appropriate guides near the top of the stack into which the said grates can he slid.

The introduction of these temporary sheet supports is extremely diflicult, and this difiiculty increases directly with the speed and size of the machine, and inversely with the quality of the paper. It is difiicult to make use of the auxiliary supports in large type high speed presses and with large soft or spongy sheets of paper. However, it is necessary that the insertion of the temporary supporting means should proceed very quickly, namely in the interval between the delivery of two consecutive sheets of paper. It also requires a considerable amount of ingenuity and celerity in high speed presses always to pick the correct moment for the insertion of the aforesaid auxiliary means. Besides, the sheets do not, as a rule, settle down on the stack as quickly as might be desired, and it often happens that they are being caught by the auxiliary supporting means. The sheets then become crumpled and the machine has to be stopped for the disturbance to be removed.

The invention, therefore, in one of its particular aspects, has for its main object the elimination of the aforesaid drawbacks, and the provision of means which will enable the insertion of'the temporary sheet supporting 'ice I means with utmost reliability at the ease of the operator and without the risk of crushing or even displacing any of the sheets in the stack.

It is also an object of the invention so to insert the auxiliary depositing means that the sheets will rest thereon perfectly flat, so that the delivery and stacking of the sheets may be continued as before.

Another object of the invention, therefore, is the provision along the edge of the auxiliary supporting device at which the incoming sheets are introduced, of means for temporarily holding the sheets, which will enable the said devices to be inserted Without any undue haste and without the risk of the sheets getting damaged. Said temporary holding or gripping means may be of the mechanic, pneumatic, electric, or any other type.

A further object of the invention is the provision of means to hold the subsequently delivered sheets so as to present a wedge-shaped space into which the auxiliary grate can be easily inserted. The holding or gripping means may be so arranged that they will hold only the first sheet which is being delivered to it, While all further sheets loosely settle thereon, or so that every sheet will be held in place by itself as by means of independent grippers or the like. It has been found suitable, in any case, to maintain the gripping means at one end or side of the stack at a certain height above the said stack, whereby the aforesaid wedge-shaped gap will be formed, into which the auxiliary grate can be inserted very easily.

A still further object of the invention is the provision of front stops for the sheet, on the stacking device which can be moved out of the Way of the auxiliary gripping means, in order to facilitate or even enable the movement of the said grippers and the introduction of the auxiliary sheet supporting means.

A particularly useful and reliable embodiment of the invention can be incorporated into a type of stacking device, in which the leading edge of the sheets, on having been released by the grippers of the delivery device, is seized by additional grippers, or suction nozzles for example, which positively forward the sheets at reduced speed against stops and thereby deposit them onto the stack. When a device in accordance with the invention is used in conjunction with a stacking device of the said type, the advantage is obtained that the leading sheet edge is guided in an exactly predetermined path and that, therefore, the grippers can be arranged to seize the edges of the sheets, the front edges in the present case, reliably at always the same place. It is evident, that each of the sheets may also be seized at any other edge instead of its front edge. Another modification, inter alia, may be that in which several grates or tables are inserted either simultaneously or successively from either the front or any other edge of the sheets.

Yet another object of the invention is the safeguarding of the sheet edges against damage. For this purpose means may be provided which will permit the operation of the gripper or grippers only at such times in which a sheet to be stacked is approaching. This can be made possible by the introduction, into the stacking device, of locking means adapted to operate in dependence of the delivery of the sheets.

A comparatively simple embodiment of the invention in a stacking device of the aforesaid type, preferably comprises an auxiliary gripper system similar to the one which above has been designated as additional. Both these systems may be composed, for instance, of suction devices, successively arranged on long depending levers and having auxiliary stops for the alignment of the sheet edges. While normally the additional gripper system receives the sheets from the delivery grippers, this secrender drawings:

into the wedge-shaped space, whereupon the. auxiliary grippers or suction devices will be returned.

It is also possible, in accordance with another object of the invention, to operate the auxiliary grippers by the means which are usedfor the temporary support of the sheets, i. e. by the grates, table tops, or the like, in which way a considerable simplification in the'manipulation of the stacking device can be obtained. In a preferred embodiment of this object of the invention the insertion of the grates over the stack of sheets may be caused, to control the auxiliary means for the clamping or, holding the sheet edges. The operator will then be able to direct his full attention to the proper handling of the grate as the sheets are seized automatically in the correct way and, therefore, requireno attention.

in an extended application of this objectfo f the invention the insertion of the grates, if guides for them are provided, can be further simplified by forming the said guides with a loop or the like, into which the front cross'bars of the grates may be suspended when not in use and so that, when they are tipped up into their horizontal slidingdn positin,-the means for gripping the sheet edge will be brought into operation. As an alternative,

the control of the auxiliary gripping means may be car ried out by the beginning of the sliding-in movement of the said grates into their guides. j

It is also possible, in accordance with the invention, to

he in operation by the application of means which will cause the automatic regulation of the auxiliary grippers during the insertion of the grate to become effective, only at such moments atwhich the nextoncoming sheet approaches the gripper or grippers.

in the latter case it is also possible to provide a locking device, whic will allow the complete introduction of the grate from its position outside the stack into its position over the stack to take place only after asheet has been seized by the auxiliary gripper and held orclamped fast 7 thereon.

The action of rendering the auxiliary gripping means inoperative by the release of the'sheets which have col- 7 lected on the grate or auxiliary stacking table is also'effected by the grate itself. This may be efiected when the grate, during its insertion, has approximately reached its end-position, or after the exchange of the main stacking tables, when the auxiliary grate or table is being Withdrawn.

The accompanying drawings illustrate several embodiments of the invention by way of example. In these Fig. '1 illustrates a comparatively simple construction of the auxiliary stacking device in accordance with the invention in side elevation with the. temporary grate or stacking table being partly introduced and with the auxiliary gripping means in their operative position.

Fig. 2 is a view similar to Fig. 1 with the'auxiliary gripping means in their position of rest.

Fig. 3 represents a front elevation ofFig. 2.

Fig. 4 illustrates in cross section a modified embodiment of the invention in which the auxiliary grippers are operated by the sheet-edge holding means in their position of rest;

a Fig. 5 shows the same modification in a view similar to Fig. 4 in its position of operation' Fig. 6 is a front elevation of Fig. 5. V Fig. 7 is a front elevation of the left hand side ofa stacking device as shown in. Figs. 4 to .6. r

Fig. 8 represents a portion of Fig. 2 showing a simple form of machine-actuated locking device, v

. Fig. 9 is a more elaborate kind of machine-controlled.

auxiliary stacking device still morev automatic locking. device in a stacking device of the type .shown 'in Figs. 2 and 8.

Fig. 10 illustrates a modification of the device shown in Figs. 4 and 5 on a smaller scale with the grate in its position of rest.

Fig. it is a view similar. to Fig. 10 with the grate in the position in which it is ready for beinginserted.

As illustrated in Figs. 1 and 2; the sheets 1 coming from the printing machine (not shown); are forwarded? shaft 6 over a depending link and lever system by the control rod 7 in a curved path which, in Figs. 1 and 2, is indicated by the dot and dash line 8. When thesuc' tion nozzle 3 meets with the delivery gripper 2 it takes. the sheet from the latter and carries it in the direction of the front stop 9 (Fig. 2), where it is released by thesuction nozzle 3 so that it falls onto the stack 11.

When the stack 11 has attained a height which was necessitate its removal, auxiliary grippers which, in thepresentcase, are, represented by suction nozzles 12 suspended on arms 12:: andhaving a stop. ledge 12b, are. moved by a link and lever system 14 from the-rocking shaft 13 into the position shown in Fig. 1. In this posi-,

tion the sheetis received by the nozzle12 from. the nozzle 3 and held along its front edgein contact with the stop. ledge 12]) by suction. For the better reception ofthe. sheets from the nozzle 3 it is advisable to lift the nozzle 12 by a corresponding movement of the link 14 and to lower it again as soon as the sheet has been taken'over, so that the suction nozzle 3, during its movement along its curved path 8, will not be able to damage the sheet; All further sheets whi h the grippers 2,3, and 12 continue to deliver will now be deposited upon the first sheet just mentioned. In this way a wedge-shaped gap is formed between these sheets and the pile 11 in'the' stacking -de'- vice, into which the auxiliary table, thegrate 15' in the present case, can be slid at the ease of the operator along the guides 17 which are provided at both sicles of the machine frame 16 and after the front stops 9 havebeenturned down as shown in Fig. 1. Owing" to this wedgeshaped space there is no danger of the sheet getting-obstructed or crushed when the grate is introduced, since it is immovably held along its front edge by the suction nozzle 12.

After the grate 15 has been completely inserted over the pile or stack 11, the suction .nozzle 12 releases the sheet and is immediately rocked back, by rotating the shaft 13, into its position of rest as shown in Fig. 2 and, for the sake of better showing, in broken lines also in Fig. l. The sheet 1 which has been held by the nozzle 12,.as well as all further sheets, are now deposited by the nozzle 3 onto the grate so as to lie perfectly flat thereon, and the stack 11 can be removed and anew stack table introduced in the conventional manner.

The modification of the auxiliary stacking device which is illustrated in Figs. 4 to 7 is also intended for cooperation with the chain conveyer for printing machines such as 2, 4, Sin the foregoing example. In the modification now to be described the front edges'of the sheets are aligned by the front stops 26 and 26a, which are a1 sesame excavation in the suction device 28 so as to rest against the end wall 31 of the said excavation when the device is at rest. The torsional force of the spring 29 can be adjusted by means of a collar 32. The mounting tube 27 is supported at both its ends in arms 33 which, in turn, are secured to the side wall 16 of the stacking device. One of these arms is preferably hollow, so that the interior of the tube 27 may be connected to a suction conduit through the said arm 33 by means of a pipe socket 34.

Guides 17 are provided below the front stops 26, 26a into which a grate 36, 36a can be pushed as a temporary support for the sheets when the stack tables are being exchanged. The said grate similar to the aforementioned grate 15, is of substantially known kind, consisting of slats or fiat bars 36, 36a connected by cross bars fore and aft. Of these cross bars the foremost bar 37 serves,

apart from supporting the sheets together with the longi- H tudinal bars or slats, also for suspending the grate in a position ready for use in the loop 17a which is formed at the forward end of the guide 17 as shown in Fig. 5.

This embodiment of the auxiliary stacking device in accordance with the invention operates as follows: When the stack 11 has reached the height which necessitates its removal, it is lowered into the position shown in Figs. 4 and 5. Grate 36, 36a, which has previously been suspended with its cross bar 37 in the loop 17a of the guide 17, is now tipped up into its horizontal position and pushed in over the stack 11. The grate bar 36a hereby encounters the cam-shaped part 38 of the suction device 23 and turns the same against the action of-spring 29 into its operative position shown in Fig. 5. The suction device with its cam-shaped portion 38 will then rest on the bar 36a as long as the grate remains in its inserted position. By the turning-up movement of the suction member 23 the bores 39 in the tube 27 register with the vacuum passage 40 of the nozzle 28 so as to cause a vacuum in the perforations 41. These perforations are in communication with the passages 40, and the sheet 1 which has just been released by the delivery grippers 2 to be deposited on the stack 11 will now be attracted by the nozzle 28 and held by the vacuum in the perforations 41 so as to maintain its position also during the insertion of the grate.

When, after the exchange of the stacks, the grate is being extracted, the spring 29 returns the suction nozzle 28 into its position of rest as shown in Fig. 4. Hereby the connection with the vacuum tube is interrupted and the sheets are free to drop onto the stack 11, or the new stack table respectively, which has meanwhile been brought into position.

Fig. 8 again illustrates the embodiment of the invention as shown in Figs. 1 to 3 but in connection with means by which the auxiliary grippers, or suction nozzles respectively, can be swung into position over the stack of sheets only under control of the printing machine. Fixed to the sprocket 5, in the enlarged embodiment represented in Fig. 8, is a cam disk 101 which at every rotation of the printing machine rocks the locking lever 102 in anticlockwise direction about its bearing pin 104. A spring 105 serves to draw the locking lever 102 with its follower 103 into contact with the cam 101. Fast on the rocking shaft 13 of the suction nozzle 12 is an abutment 106 which permits the suction nozzle to be swung over the stack 11 by means of the hand lever 107 that is also secured to the rocking shaft 13 oniy when the locking lever 162 is in the release position shown in Fig. 8, in which the free end of the locking lever is lowered to underneath the abutment 166 by the rise 1% on the cam 191. This prevents the auxiliary nozzle from being extended at an improper time which would interfere with other parts of the machine.

Whereas in the foregoing example the swinging of the auxiliary gripper, or the suction nozzle respectively, de' pends on the movement 'of the arms 12a by a hand lever, Fig. 9 illustrates a further enlargement according to which the swinging-in of 'the auxiliary suction nozzle 12 is controlled by the machine to take place at always the correct moment after the grate 15 has been tipped up irom its position of rest 261 into its position of preparedness 2632. For this purpose the driving means 13 are provided with an abutment pin 203-which, when the gripper 12 is in its position of rest, bears against the locking lever 265 under the action of a spring 2%. This locking lever 2115 has two arms at approximately right angles to each other and is pivoted on a pin 206 in the standard 16 of the stacking device. Its depending arm is provided with a roller 208 and a spring 207 is used to keep this roller in contact with a control cam 2%, which is fixed to the sprocket wheel 5 and makes one complete revolution at each printing operation of the machine. When the suction nozzle is not in use, roller 208 is drawn by the three-armed control lever 210 into the position shown in broken lines, in which the suction nozzle is held in its inoperative position by the horizontal lever arm 2115 as shown in Fig. 9. In this position the three-armed control lever is drawn by the spring 211 into contact with a stop 212.

If now the grate 15 is lifted from its position of rest 2131 into its position of working preparedness 2132, its pertaining grate bar lifts the roller 213 f the control lever 210 and moves the same into theposition which is shown in full lines. When now the drop or recess 214 in the cam 269 assumes the position shown in the drawing, roller 208 will be able to enter into this recess. By this means the locking lever 205 releases the abutment pin 203 and the suction nozzle 12 will be swung by the spring 204 into its operative position, which however, is limited by the lever arm 215 coming into contact with the stop 216.

The suction nozzle 12 is supplied with'the required vacuum over the conduit 218 in which a stop valve 219 is arranged, which is opened by the arm 220 of the control lever 21% on the roller 213 being lifted.

Another stop valve 221 is provided in the conduit 218 which closes the conduit when the grate 15 has been fully inserted by pressing the spindle 223 of the valve inwardly. in this way the connection of the nozzle 12 with the vacuum pump, which is joined up to the pipe 222, becomes interrupted.

As shown in Figs. 10 and 11 the suction device 199 may be actuated when the grate 36, 36a is tipped up from the depending position of Fig. 10 into the horizontal position shown in Fig. 11 and pushed slightly inward. In this position the pertaining grate bar lifts the roller 111 of the toothed segment 112 and thereby imparts to it a turning movement in clockwise direction. At the same time the suction device 199 is swung from its inoperative into its operative position over the stack 11 in order thereby to attract the sheet 1 which is being delivered by the printing machine. The toothed segment 112 is pivoted on the bolt 114 which is fixed to the arm 115 of the front stop 26a of the stacking device.

What we claim is:

1. A sheet stacking apparatus for sheet printing machines, means for exchanging the stack support during the continued operation of the machine in combination with front stops, an auxiliary sheet support for insertion over the stack on the said stack support and with means for guiding said auxiliary sheet support over the stack, a hollow suction tube, a gripper turnable on said tube, suction nozzles on said gripper, means in connection with said auxiliary sheet support for moving said gripper into a sheet receiving and holding position, and means for supplying a vacuum into said hollow tube.

2. A sheet stacking apparatus for sheet printing machines, means for exchanging the stack support in combination with front stops, an auxiliary sheet support for insertion over the stack on said stack support'andfwith means for guiding said auxiliary sheet support over the stack so as to receive and support the sheets while the auxiliary support is inserted, a hollow suction tube, a gripper turnable on said tube and depending into the path of said sheet support whenthe latter is moved over the stack, means in connection with said-auxiliary sheet support for pivoting said gripper upwardly into a sheet'receiving position, suctionnozzles on said gripper, passages between said nozzles and the interior of said.

. suction tube normally out of communication but moved into'register by the upward pivoting of said sheet support, and a guide for moving said sheet support over the stack thereby to contact with and temporarily pivot said gripper into a position for receiving and holding sheets which are delivered during the time in which an exchange of the, stack support takes. place in the stacking device.

3. A sheet stacking apparatus for sheet printing machines, means for exchanging the stack support, comprising, in combination with front stops, an auxiliary sheet support for insertion over the stack on said'staclt support, and means for guiding said auxiliary sheet support over the stack so as to receive and support the sheets while the said auxiliary support is inserted, a hollow suction tube, a gripper turnable on said tube, suction f nozzles on said gripper, said gripper depending into the path of said auxiliary sheet support to contact therewith so as to be moved bythe said sheet support into a sheet receiving and holdingjposition, and suction passages to establish communication between the said suction nozzles and said hollow tubewhen the said gripper has been moved into its sheet receiving position.

4. A sheet stackingapparatus for sheet printing machines, means for exchanging the stack support, comprising, in combination with front stops, an auxiliary sheet support for insertion over the stack on said stack support, and means tor guiding said auxiliary sheet support over the'stack so as to receive and support the sheets while the said auxiliary support is inserted, a hollow. suction tube, a bore in the wall of said tube, a gripper turnable'on said tube,.suction nozzles along the inner edge of said. gripper, a suction passage in said gripper in connection with said suction nozzles, a. bore 6. A sheet stacking apparatus for sheet printing machines, in combination with: means for exchanging the .stack support during the operation of the machine and the stacking device,'an auxiliary sheet support for insertion over the stack on said stack support, a guide for guiding said, auxiliary sheet support over the stack so as to receive and support the sheets while the said auxiliary support is inserted, an auxiliary gripper movable for gripping sheets which are delivered from the printing machine during the exchange of the stack support, suction means on said gripper for holding said sheets along their leading edges, a loop at the end of said guide, means at the leading end of said auxiliary sheet support for, suspending said sheet support in saidloop, and means on, said auxiliary gripper responsive to the tipping-up and sliding-in movement of said sheet support for gripping a sheet and holding it along its leading in said tube wall normally out of communication with said passage, a cam portion on said gripper suspending into the path, of said sheet support, a guide for the said auxiliary sheet support over the stack of sheets, and means on said guide to suspend said auxiliary sheet support out or" operation and so as to be raised into contact 7 with said cam portion of said gripper'to pivot same and to affordcommunication between the said passage in the gripper and the bore in thewall of said tube.

. 5. A sheet stacking apparatus for sheet printing machines having a main stack support and means for the exchange of the said main stack support, an auxiliary sheet support for insertion over the stack on said stack support, means for temporarily moving said sheet support over thejstack so as to receive and support the sheets while the said auxiliary support is inserted, front stops above the forward end of said stacking device, a hollow tube to carry said front stops with their sheetstopping surfaces in a vertical position facing the oncoming sheets, a depending gripper turnably suspended from said hollow tube, suction passages in said gripper extending to the. outside thereof, the wall of said hollow tube having a normally closed bore, means for turning said auxiliary gripper into its operating position with its suction passages to register with the bore in said tube wall, a cam portion on said gripper extending into the path of said auxiliary sheet support thereby to contact with said cam portion. and to move said gripper into a sheet receiving position with" its suction passages communicating with said bore in the tube wall and to hold the leading edge of said sheets while said auxiliary sheetsupport is being movedalong said guide.

edge while said auxiliary sheetfsupport is being-moved.

over the said stack.

77 A sheet stacking apparatus for sheet printing machines, in combination with means for exchanging the stack support, an, auxiliary sheet support for insertion over the stack onsaid stack support, a guide for guiding a said auxiliary sheet support over the stack so as to receive and support the sheets while the said auxiliary support is inserted, a' loop at the front of said guide for suspending said auxiliary sheet support therein, a hollow shaft horizontally disposed above said stack and guide 7 having a perforation in its'wall, a front stop in fixed position on said hollow shaft, an auxiliary gripper turnable on said hollow shaft, suction means on said gripper for seizing a sheet and holding it along its leading edge and against said front stops, gear teeth on said .aux-

iliary gripper, a pivoted gear in engagement with said gear teeth on said auxiliary gripper, and means on said pivoted gear for contacting with said auxiliary sheet sup- .port when the latter is being turned up in its loop'to.

turn said auxiliary gripper into itsoperative position.

8. A sheet stacking apparatus for sheet printing machines as setforth in claim 3,'in which the means which respond to the insertion of theauxiliary sheet support for putting said gripping means into operation also respond to the removal of the said auxiliary sheet support for placiug said gripping means out of operation. 7

9. A sheet stacking apparatus for sheet printing'machines having a main stack support, a gripper arranged adjacent to said support, a conveyor for delivering in dividual sheets to said gripper, said gripper having means for depositing said sheets upon said main stack support,

selectively actuated means for temporarily suspending one end of delivered sheets above said stack and an auxiliary sheet support supported for reciprocating movement to a position between said selectively actuated means and said stack,'saidj auxiliary sheet support Whenin said position being operative to receive said suspended sheets from said selectively actuated means and said gripper;

10. A sheet stacking apparatus as set forth in claim 9, V wherein, said selectively actuating means comprises a suction apparatus for receiving the-leading edges of sheets from said conveyor means, said main stack support having spaced guides for directing the movement of said auxiliary sheet support to said position. 7 11. A sheet stacking apparatus as set forth in claim 9,

wherein said conveyor comprises a continuous chain for ing movement to said position.

12. A sheet stacking apparatus as setforth in claim 9,

wherein said selectively actuated means is operative to.

support a plurality of printed sheets from said gripper and has retraction means for disengaging said sheets upon movementof-said auxiliary sheet support to said position see ers for releasing said suspended sheets for flat face engagement with said auxiliary sheet support.

13. A sheet stacking apparatus as set forth in claim 9, further comprising control means for effecting timed reciprocating movement of said gripper, said selectively actuated means including suction means for temporarily holding the leading edge of at least one sheet received from said gripper during movement of said auxiliary sheet support to said position, and means for effecting reciprocating movement of said selectively actuated means at least once during movement of said auxiliary sheet support into and out of said position.

14. A sheet stacking apparatus for sheet printing machines having a main stack table and auxiliary means for continuing the stacking operation during the exchange of the main stacl: table including an auxiliary stacking table for temporary insertion over the stack, chain grippers for delivering the printed sheet from the printing machine to the stacking device, an additional gripper comprising a suction nozzle for receiving the sheets from said chain grippers, means for efiecting timed reciprocating movement of said additional gripper, a grate serving as said stacking table, a guide on either side of the stack at the same height thereof for receiving said grate during the exchange of the main stack table, rotatable from stops rotatahly carried by said machine and adapted to be turned down during sliding movement of said grate into said guides, an auxiliary gripper for receiving grates from said additional gripper, suction means on said auxiliary gripper for temporarily holding the leading edge of the sheets received, a front stop on said auxiliary gripper, and means for reciprocating said auxiliary gripper into and out of its sheet receiving position.

15. A sheet stacking apparatus for sheet printing machines having a stack table and auxiliary means for continuing the stacking operation during the exchange of the main stack table including an auxiliary sheet table, chain grippers tor deiivering the printed sheets to the stacking device, additional gripper for receiving the sheets from said chain grippers and depositing them upon the stack, an auxiliary gripper effective during the exchange of the main stack table for taking over at least one sheet from said additional gripper and depositing it upon said stack so as to leave a wedge shaped space above said stack, suction means on said auxiliary gripper for holding the sheet along its leading edge during the insertion of said auxiliary table into said wedge shaped space, means for reciprocating said additional gripper, separate means for reciprocating said auxiliary gripper,

1% and a locking device associated with said auxiliary gripper comprising a manually controlled lever, said manually controlled lever being operatedin the sequence of the sheet delivery whereby movement of said auxiliary gripper is permitted in response to the approach of the sheet to be stacked.

16. A sheet stacking apparatus for said printing machines having a stack table and auxiliary means for continuing stacking operation during the exchange of the main stack table including an aux liary sheet table, chain grippers for delivering the printed sheets to the stacking device, an additional gripper for receiving the sheets from said chain grippers and depositing them upon the stack, an auxiliary gripper efiective during the exchange of the main stack table for receiving at least one sheet from said additional gripper and depositing it upon said stack so as to leave a Wedge-shaped space above said stack, suction means on said auxiliary gripper for holding said sheet along its leading edge during the insertion of said auxiliary sheet table into said Wedge-shaped space, means for reciprocating said additional gripper, separate means for reciprocating said auxiliary gripper, a locking device comprising an adjustable stop on said auxiliary gripper, cam means operating in the sequence of the sheet delivery, a stop lever operated by said cam means in cooperation With said adjustable stop, and a release lever responsive to the insertion of said auxiliary sheet table and to return said stop lever to the control of said cam means in response to the removal of said auxiliary sheet table.

17. A sheet stacking apparatus as set forth in claim 16, wherein said release lever includes means for activating said auxiliary gripper in response to insertion of said auxiliary sheet table.

18. A sheet stacking apparatus as set forth in claim 16, further comprising a suction conduit, a stop valve in said suction conduit, and a closing spindle in said stop valve, said closing spindle being positioned in the line of inward movement of said auxiliary table so as to be closed in response to the insertion of said auxiliary sheet table.

References Cited in the file of this patent UNITED STATES PATENTS 

